Water Damage

Melting permafrost is changing the very chemistry of the great rivers of the North.
No one really knows what this will mean for life in the region… or the planet

About 15 years ago, I travelled to Sachs Harbour, an Inuvialuit
settlement of about 100 residents on Banks Island in the westernmost
part of the Arctic Archipelago. Back then, scientists were
starting to become aware that this part of the world was warming up at two
and three times the global average as a result of the growing load of carbon
dioxide in the atmosphere. The signs were everywhere. Robins and mosquitoes
were showing up for the first time in memory, drawn north by the new
warmth. And the graves of the community’s elders, set upon the permafrost
on a hill overlooking the Arctic Ocean, had begun to sink in the heat. It was
an assault on the Inuvialuit sensibility, among much else. To them, the
permafrost was alive. They felt they were witnessing its death.

Since then, the melting of the planet’s
permafrost increasingly has been on climate
researchers’ radars. It is a particular concern
in Canada, since this permanently frozen
ground, from just centimetres below the
surface to metres deep, underlies roughly
half of our country’s total land mass.

Back when I was up in Sachs Harbour,
the primary concern was how the melt
would affect the people whose communities
were perched on it. In the years since, the scientific focus has been on the fact that melting permafrost releases
methane — long stored in the frozen ground — into the atmosphere.
Methane is about 20 times more efficient at trapping heat against the
Earth’s surface than carbon dioxide. The race has been to figure out
how much the released methane will affect the planet’s warming and
how fast. Stay tuned.

Now, a pair of studies published late in 2016 look at a new facet of the
problem. Using decades of data, they examine how permafrost melt is
affecting water chemistry in the Yukon River and Mackenzie River basins.
Together, these basins encompass nearly 2.7 million square kilometres of
the frozen North.

It turns out that as permafrost melts, it allows water to flow to new
reaches of the once-frozen soil, as well as into bedrock and groundwater.
That running water picks up minerals that used to be locked in the ground,
carrying them along the rivers and into the ocean in great pulses or fluxes.
And that is changing the chemistry of the water in the rivers. Dramatically.
Not just in summer, when more water is on the move anyway, but in the
fall and winter, too, when it ought to be more sedate.

The Yukon River originates in northwestern British Columba, passes
through Yukon and Alaska and ends up pouring water into the Bering Sea.
In all, it covers an area about the size of California. In turn, the Bering
Sea feeds the mineral-laden water into the Arctic Ocean. The study on the
Yukon River basin shows that the flowing water contains such oddities as
higher concentrations of sulphate, calcium, magnesium, sodium, potassium
and dissolved organic carbon than it did three decades ago. The yearly
sulphate flux alone is 60 per cent greater, and phosphorus 200 per cent
higher in December.

One of the great truths of nature is that chemistry determines biology.
So what’s this vastly different chemistry doing?

Researchers are starting to investigate how
this ‘new pulse of weird chemistry’ contained
in all that fresh water will affect the workings
of the Bering Sea and Arctic Ocean

Alanna Mitchell

I asked Ryan Toohey, the hydrologist at
the Alaska Climate Center in Anchorage
and lead author on the Yukon River study,
for details. He said a lot more research is
being done on the fallout. But one of the
worries is that higher concentrations of
sulphates could end up putting more toxic
mercury into circulation through
microbial activity. Not a good sign for life.

The effects aren’t just going to be felt in
the river basins that run through melting
permafrost. Researchers are investigating
how that new pulse of weird chemistry,
contained in all that fresh water, will
affect the workings of the Bering Sea and
Arctic Ocean.

That matters because the Arctic Ocean
is like a thermostat for the planet, helping
control ocean currents and therefore
climate. And already, the Arctic Ocean is
stressed. All that extra warmth in the
atmosphere means the ocean has less and
less ice cover. That means the Arctic Ocean is
holding more heat in its dark waters, raising
water temperatures. Add to that this change
in its very chemistry, and it could spell even
more impairment of the ocean currents
that our planet’s climate systems rely on.

Piece by piece, from air temperature to
water temperature to the melting permafrost
to the chemistry of its galloping rivers, this
critical component of the Earth’s system is
changing dramatically. Just as the impacts of
climate change were barely imaginable back
when I was up in Sachs Harbour a decade and
a half ago, the likely impact of such massive
change is still largely unknown.

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